Conventionally, when a user photographs a product of interest and transmits a product image to a product sale site, information of the product identified through an image matching process is returned. For example, a service of identifying a book through the image matching process and returning feature information such as a summary and a price of the book to a user terminal when a cover image obtained by photographing a cover of the book is received from the user terminal was performed at an online store in a site described in Non-Patent Literature 1.